Structure and temperature-dependent phase transitions of lead-free Bi1/2Na1/2TiO3-Bi1/2K1/2TiO3-K0.5Na0.5NbO3 piezoceramics
- TU Darmstadt
Structure and phase transitions of (1-y)((1-x)Bi1/2Na1/2TiO3-xBi1/2K1/2TiO3)-yK0.5Na0.5NbO3 (x; y) piezoceramics (0.1 ≤ x ≤ 0.4; 0 ≤ y ≤ 0.05) were investigated by transmission electron microscopy, neutron diffraction, temperature-dependent x-ray diffraction, and Raman spectroscopy. The local crystallographic structure at room temperature (RT) does not change by adding K0.5Na0.5NbO3 to Bi1/2Na1/2TiO3-xBi1/2K1/2TiO3 for x = 0.2 and 0.4. The average crystal structure and microstructure on the other hand develop from mainly long-range polar order with ferroelectric domains to short-range order with polar nanoregions displaying a more pronounced relaxor character. The (0.1; 0) and (0.1; 0.02) compositions exhibit monoclinic Cc space group symmetry, which transform into Cc + P4bm at 185 and 130 °C, respectively. This high temperature phase is stable at RT for the morphotropic phase boundary compositions of (0.1; 0.05) and all compositions with x = 0.2. For the compositions of (0.1; 0) and (0.1; 0.02), local structural changes on heating are evidenced by Raman; for all other compositions, changes in the long-range average crystal structure were observed.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- FOREIGNUNIVERSITY
- OSTI ID:
- 1048960
- Journal Information:
- Journal of Materials Research, Vol. 2012, Issue (27) ; 10, 2012; ISSN 0884-2914
- Publisher:
- Materials Research Society
- Country of Publication:
- United States
- Language:
- ENGLISH
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